#pragma once
#include <algorithm>
#include <map>
#include <string>
#include "quic_bandwidth.h"
#include "quic_unacked_packet_map.h"
#include "quic_connection_stats.h"

namespace quic {
	typedef uint64_t QuicRoundTripCount;
	class CachedNetworkParameters;
	class RttStats;

	class  SendAlgorithmInterface {
	public:
		// Network Params for AdjustNetworkParameters.
		struct  NetworkParams {
			NetworkParams()
				: NetworkParams(QuicBandwidth::Zero(), QuicTime::Delta::Zero(), false) {
			}
			NetworkParams(const QuicBandwidth& bandwidth,
				const QuicTime::Delta& rtt,
				bool allow_cwnd_to_decrease)
				: bandwidth(bandwidth),
				rtt(rtt),
				allow_cwnd_to_decrease(allow_cwnd_to_decrease),
				quic_fix_bbr_cwnd_in_bandwidth_resumption(
					true),
				quic_bbr_fix_pacing_rate(
					false),
				quic_bbr_donot_inject_bandwidth(
					false) {}

			bool operator==(const NetworkParams& other) const {
				return bandwidth == other.bandwidth && rtt == other.rtt &&
					allow_cwnd_to_decrease == other.allow_cwnd_to_decrease &&
					quic_fix_bbr_cwnd_in_bandwidth_resumption ==
					other.quic_fix_bbr_cwnd_in_bandwidth_resumption &&
					quic_bbr_fix_pacing_rate == other.quic_bbr_fix_pacing_rate &&
					quic_bbr_donot_inject_bandwidth ==
					other.quic_bbr_donot_inject_bandwidth;
			}

			QuicBandwidth bandwidth;
			QuicTime::Delta rtt;
			bool allow_cwnd_to_decrease;
			// Code changes that are controlled by flags.
			// TODO(b/131899599): Remove after impact of fix is measured.
			bool quic_fix_bbr_cwnd_in_bandwidth_resumption;
			// TODO(b/143540157): Remove after impact of fix is measured.
			bool quic_bbr_fix_pacing_rate;
			// TODO(b/72089315, b/143891040): Remove after impact of fix is measured.
			bool quic_bbr_donot_inject_bandwidth;
		};

		static SendAlgorithmInterface* Create(
			const QuicClock* clock,
			const RttStats* rtt_stats,
			const QuicUnackedPacketMap* unacked_packets,
			CongestionControlType type,
			QuicConnectionStats* stats,
			QuicPacketCount initial_congestion_window);

		virtual ~SendAlgorithmInterface() {}


		// Sets the initial congestion window in number of packets.  May be ignored
		// if called after the initial congestion window is no longer relevant.
		virtual void SetInitialCongestionWindowInPackets(QuicPacketCount packets) = 0;

		// Indicates an update to the congestion state, caused either by an incoming
		// ack or loss event timeout.  |rtt_updated| indicates whether a new
		// latest_rtt sample has been taken, |prior_in_flight| the bytes in flight
		// prior to the congestion event.  |acked_packets| and |lost_packets| are any
		// packets considered acked or lost as a result of the congestion event.
		virtual void OnCongestionEvent(bool rtt_updated,
			QuicByteCount prior_in_flight,
			QuicTime event_time,
			const AckedPacketVector& acked_packets,
			const LostPacketVector& lost_packets) = 0;

		// Inform that we sent |bytes| to the wire, and if the packet is
		// retransmittable.  |bytes_in_flight| is the number of bytes in flight before
		// the packet was sent.
		// Note: this function must be called for every packet sent to the wire.
		virtual void OnPacketSent(QuicTime sent_time,
			QuicByteCount bytes_in_flight,
			QuicPacketNumber packet_number,
			QuicByteCount bytes,
			HasRetransmittableData is_retransmittable) = 0;

		// Inform that |packet_number| has been neutered.
		virtual void OnPacketNeutered(QuicPacketNumber packet_number) = 0;

		// Called when the retransmission timeout fires.  Neither OnPacketAbandoned
		// nor OnPacketLost will be called for these packets.
		virtual void OnRetransmissionTimeout(bool packets_retransmitted) = 0;

		// Called when connection migrates and cwnd needs to be reset.
		virtual void OnConnectionMigration() = 0;

		// Make decision on whether the sender can send right now.  Note that even
		// when this method returns true, the sending can be delayed due to pacing.
		virtual bool CanSend(QuicByteCount bytes_in_flight) = 0;

		// The pacing rate of the send algorithm.  May be zero if the rate is unknown.
		virtual QuicBandwidth PacingRate(QuicByteCount bytes_in_flight) const = 0;

		// What's the current estimated bandwidth in bytes per second.
		// Returns 0 when it does not have an estimate.
		virtual QuicBandwidth BandwidthEstimate() const = 0;

		// Returns the size of the current congestion window in bytes.  Note, this is
		// not the *available* window.  Some send algorithms may not use a congestion
		// window and will return 0.
		virtual QuicByteCount GetCongestionWindow() const = 0;

		// Whether the send algorithm is currently in slow start.  When true, the
		// BandwidthEstimate is expected to be too low.
		virtual bool InSlowStart() const = 0;

		// Whether the send algorithm is currently in recovery.
		virtual bool InRecovery() const = 0;

		// True when the congestion control is probing for more bandwidth and needs
		// enough data to not be app-limited to do so.
		// TODO(ianswett): In the future, this API may want to indicate the size of
		// the probing packet.
		virtual bool ShouldSendProbingPacket() const = 0;

		// Returns the size of the slow start congestion window in bytes,
		// aka ssthresh.  Only defined for Cubic and Reno, other algorithms return 0.
		virtual QuicByteCount GetSlowStartThreshold() const = 0;

		virtual CongestionControlType GetCongestionControlType() const = 0;

		// Notifies the congestion control algorithm of an external network
		// measurement or prediction.  Either |bandwidth| or |rtt| may be zero if no
		// sample is available.
		virtual void AdjustNetworkParameters(const NetworkParams& params) = 0;

		// Retrieves debugging information about the current state of the
		// send algorithm.
		virtual std::string GetDebugState() const = 0;

		// Called when the connection has no outstanding data to send. Specifically,
		// this means that none of the data streams are write-blocked, there are no
		// packets in the connection queue, and there are no pending retransmissins,
		// i.e. the sender cannot send anything for reasons other than being blocked
		// by congestion controller. This includes cases when the connection is
		// blocked by the flow controller.
		//
		// The fact that this method is called does not necessarily imply that the
		// connection would not be blocked by the congestion control if it actually
		// tried to send data. If the congestion control algorithm needs to exclude
		// such cases, it should use the internal state it uses for congestion control
		// for that.
		virtual void OnApplicationLimited(QuicByteCount bytes_in_flight) = 0;

		// Called before connection close to collect stats.
		virtual void PopulateConnectionStats(QuicConnectionStats* stats) const = 0;
	};
}	// namespace quic

